3v4l.org

run code in 200+ php & hhvm versions
Bugs & Features
<?php $s = '123_abc____def'; var_dump( preg_replace_callback( '/\_+[a-zA-Z]{1}/e', function($matches){return '_' . strtoupper($matches[1]);}, $s) );
based on rdcOB
Output for 7.0.20, 7.1.5 - 7.2.6
Warning: preg_replace_callback(): The /e modifier is no longer supported, use preg_replace_callback instead in /in/68U8V on line 9 NULL
Output for 7.0.0 - 7.0.6, 7.1.0
Warning: preg_replace_callback(): The /e modifier is no longer supported, use preg_replace_callback instead in /in/68U8V on line 8 NULL
Output for 5.3.21 - 5.6.21
Warning: preg_replace_callback(): Modifier /e cannot be used with replacement callback in /in/68U8V on line 9 NULL